These Leland CO2 TapGas cylinders are 74 grams each and have 5/8" threaded necks. They are packaged in a convenient 2 pack, allowing you to use both cylinders for 1/2 kegs or use only 1 cylinder for 1/4 and 1/6 kegs. Each cylinder is designed for use with the Leland CO2 PicnicTap Beer Pump and are perfect for tailgating and other outdoor events.